For Linux based users its their habit to open applications/softwares with keyboards shortcuts, but unfortunately there are no default keyboard shortcuts in mac.
You can use “Spotlight Search”. Spotlight is system wide search application which is used to search anything in your mac os x.
To open Terminal with spotlight, just press
⌘(Command) + Space, type “Terminal” and then hit “Enter”
It will open “terminal” application however, this is not exactly the kind of keyboard shortcut to open terminal in Mac which you are looking for, but its better than pressing F4 and opening terminal.
Spotlight search was released with Mac OS X 10.4, so that means it will work with Mac OS X 10.10 Yosemite, Mac OS X 10.9 Mavericks and other previous versions.